MEMS Microphone Vacuum Chamber Magnetoresistive Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MEMS microphones face limitations in achieving high signal-to-noise ratio due to air viscosity and require large back cavities, which restricts miniaturization and increases noise, affecting mechanical sensitivity and overall size.
Innovation Solution
An MEMS microphone design featuring a vacuum chamber between the vibration diaphragm and substrate, equipped with a magnetic film and magnetoresistive sensor, reduces air viscosity and eliminates the need for a large back cavity, enhancing signal-to-noise ratio and allowing for a smaller form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large back cavity is designed to improve mechanical sensitivity, then the mechanical sensitivity of the vibration diaphragm is improved, but the overall size of the microphone increases and miniaturization is restricted
Solution Approach 1:
The patent changes the pressure parameter from atmospheric pressure to vacuum pressure in the back cavity. This parameter change eliminates the need for a large back cavity because vacuum conditions eliminate air viscosity effects that would otherwise block air circulation and reduce mechanical sensitivity. The vacuum environment allows the vibration diaphragm to maintain high mechanical sensitivity even in a compact structure.
Solution Approach 2:
The patent creates a vacuum environment (inert atmosphere without air molecules) in the back cavity. This eliminates the harmful effect of air viscosity that would otherwise require a large back cavity for proper air circulation. The vacuum environment allows the system to achieve high mechanical sensitivity without needing the space for air flow that would be required in an atmospheric pressure system.
2Stability of the object's composition
If dense perforation holes are designed in the backplate for pressure equalization, then pressure equalization is improved, but air flow resistance increases and noise increases
Solution Approach 1:
The patent extracts air from the back cavity to create a vacuum environment. This removes the source of air flow resistance and noise generation entirely. Without air molecules present, there is no air viscosity to create flow resistance through the perforation holes, thereby eliminating the dominant noise source while still allowing pressure equalization to occur through the vacuum state.
3Volume of moving object
If the volume of the back cavity is reduced for miniaturization, then the overall size is reduced, but air circulation is blocked and mechanical sensitivity decreases
Solution Approach 1:
The patent changes the pressure parameter from atmospheric to vacuum, which fundamentally alters the physics of air circulation. In a vacuum environment, there is no air to circulate or create viscosity effects, so the mechanical sensitivity is not degraded by reduced cavity volume. This parameter change allows miniaturization without sacrificing performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design improves mechanical sensitivity and reduces noise by lowering air viscosity within the vacuum chamber, increasing the signal-to-noise ratio and enabling a more compact microphone structure with improved reliability.
Implementation Method 1
the other one of the vibration diaphragm and the first substrate is provided with a magnetoresistive sensor cooperating with the magnetic film, the magnetoresistive sensor being configured to sense a change in a magnetic field of the magnetic film during a vibration of the vibration diaphragm and output a varying electrical signal
Data Source
AI summary
An MEMS microphone is provided, comprising a first substrate and a vibration diaphragm supported above the first substrate by a spacing portion, the first substrate, the spacing portion, and the vibration diaphragm enclosing a vacuum chamber, and a static deflection distance of the vibration diaphragm under an atmospheric pressure being less than a distance between the vibration diaphragm and the first substrate, wherein: one of the vibration diaphragm and the first substrate is provided with a magnetic film, and the other one of the vibration diaphragm and the first substrate is provided with a magnetoresistive sensor cooperating with the magnetic film, the magnetoresistive sensor being configured to sense a change in a magnetic field of the magnetic film during a vibration of the vibration diaphragm and output a varying electrical signal.